Cyano ether-ester copolymer



United States Patent 2,828,295 CYANO ETHER-ESTERY COPOLYME John Mann Butler, Dayton, Ohio, assighor' to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing; Application September 1, 1955 Serial No. 532,118

Claims. (Cl. 260 -855) This invention relates to new copolymers which are capable of fabrication into desirable transparent flexible films. More particularly the invention relates to copolymers of acrylonitrile and certain cyano ether-esters.

The primary purpose of this invention is to prepare novel synthetic elastomeric. compositions having an unusual combination of flexibility and solvent resistance. A futher purpose of this invention is to provide new elastomeric compositions foruse in the coatings industry. Still another object is the provision of improved emulsion latices for the coatings industry.

It has been found that certain cyano ether-esters and acrylonitrile give very desirable compositions when copolymerized in suitable proportions. The preferred proportions employed for producing the new copolyme'rs may consist generally of from 30 to 95 percent of the cyano ether-ester, although the more valuable products are prepared utilizing from 40 to 90' percent by'weight of the ester in the copolymer, with the balance being acrylonitrile.

The cyano esters useful for the preparation of the pres ent copolymers are acrylates having the formula CH :CH.COOCH (CH CH OCH CH CN in which n is an integer of from 1 to 2.

Compounds having the aboveformula are disclosed in my copending application Serial No. 337,241, filed February 16, 1953, now issued as U. S. Patent No; 2,720,512, dated October 11, 1955, of which application this is a continuation-impart. They are obtainable by contacting, in the presence of an esterifying agent, acrylic acid or an acid halide thereof such as acrylyl chloride with a hydroxy alkoxy nitrile selected from the class consisting of 4-(2-cyanoethoxy)-l-butanol and l3e(2-cyanoethyoxy)- l-propanol. Hydroxyalkoxynitriles having this formula are easily obtainable by the addition reaction of acrylonitrile and 1,4-butanediol or 1,3-propanediol.

Cyano ether-esters which may be copolymerized with acrylonitrile to yield the present synthetic elastomers are 4-(2-cyanoethoxy)butyl acrylate and 3-(2-cyanoethoxy)- propyl acrylate.

The new copolymers maye be prepared by any of the several polymerization methods known to the art, but the emulsion polymerization method is the most effective. In the practice of the emulsion polymerization technique, monomers are contacted in the presence of water which contains dissolved therein a suitable peroxy catalyst and preferably an emulsion stabilizing agent. If desired, all of the monomers may be charged to the polymerization reactor at the beginning of the reaction, or they may be added periodically or gradually throughout the course of the reaction. Similarly, the catalyst and emulsifying agents may also be introduced either at the start or in increments during the reaction. The preferred method of conducting the polymerization involves the mixing of the monomers in the desired proportions and adding the A 2,828,295 ..Ps*ne4-Ms':? 3

the polymerizable compound; The catalyst may be charged at the beginning of the reaction or. it may be added continuously or in increments throughout the course of the reaction for the purpose of maintaininga more uniform concentration of catalyst in the reaction mass. The latter method is preferred because it tends to make the resultant polymer more uniformin physical and chemical properties.

Although the uniform distribution of the reactants throughout the reaction mass can be achieved by vigorous agitation, it is generally desirable to promote the uniform distribution of reagents by using wetting agents, or emulsion s'tabilizers. Suitable agents for this purpose are the water-soluble salts of fatty acids, such as sodium oleate, and potassium stearate, mixtures of water-soluble fatty acid salts, such as the common soaps prepared by the saponification of animal and vegetable oils, the amino soaps, such as triethanolamine and dodecyl methyl amine, salts of rosin acids and mixtures thereof, the water-soluble salts of half esters of sulfuric acid and long chain alkyl alcohols, sulfonated hydrocarbons, such as alkyla'rylsulfonates, and any other of the wide variety of wetting agents, which are in general organic compounds containing both hydrophobic and hydrophilic radicals. The quantity of emulsifying agent will depend upon the particular agent selected, the ratio of monomer to be used, and the conditions of polymerization. In general, however, from' 0.1' to 5 percent by weight of the monomer may be employed.

The emulsion polymerization reactions are conducted at temperatures between 30 and 70 C., but preferably at the reflux temperature of the emulsion. The polymerization temperatures should be maintained substantially constant, and by operation at reflux temperatures the rate of addition of the monomers may be regulated so as to maintain the temperature more nearly constant. Under such conditions the optimum quantity of the product is obtained.

The reaction is preferably initiated by charging the re actor with water containing the catalyst and emulsifier in solution, and thereafter adding the monomer gradually at rates which enable the maintenance of a constant temperature. If desired, the monomers may each be added in a separate stream of premixed monomer. In order to avoid unduly high concentrations of emulsifier in the reaction mass at the beginning of the reaction most of it may be mixed with the monomer and added therewith during the reaction. Preferably, only a small-proportion of the catalyst is charged at the beginning of the reaction and the remainder is added either continuously or intermittently throughout the course of the reaction. The preferred manner of operation involves heating the water containing a small amount of catalyst and emulsifier to approximately the ultimate polymerization temperature and initiating the reaction by introducing the stream of mixed monomers.

The emulsion polymerizations are conducted in metal, glass or glass lined vessels, Which are provided with means for agitating the contents thereof. Generally, rotary stirring devices are the most effective means of insuring the intimate contact of the reagents, but other man A ings because they display very good resistance to many solvents, particularly to the aromatic and aliphatic hydrocarbons, aliphatic alcohols and esters and the lower chlorinated alkanes. The latices can be pigmented in the formulation of coatings. The present latices are also useful as solvent resistant adhesives. Films cast from emulsions of the present copolymer have good flexibility and color.

Further details of the practice of this invention are set forth with respect to the following specific examples:

Example 1 A mixture consisting of grams of 3-(2-cyanoethoxy)-propyl acrylate, 10 grams of acrylonitrile, 190 cc. of water, 0.3 gram of a sodium lauryl sulfate emul- "asasaos sifier known to the trade as Duponol MB, 0.1 gram I of potassium persulfate and 0.02 gram of sodium bis'ulfits was charged to a flask. The flaslcwas swept out with nitrogen and sealed, and then placed on a rotating rack and maintained thereon at 43 R. P.- M. for a time of 33 hours at a temperature of 55 C. The reaction mixture was then filtered to remove the small quantity of solid which was present. A film cast from the filtrate on a glass plate was flexible, clear and colorless. It was found to be resistant to water, benzene, toluene, ethyl acetate, carbon tetrachloride, hexane, and methanol. When tes ed by the Clash-Berg method, a molded test specimen of the copolymer had a low-temperature flexibility value of minut 8 C. and a Stifilex range of T =23 C.

Example 2 Films cast from the resulting filtered emulsion Operating as in the above examples emulsion latices of copolymers of 4-(2-cyanoethoxy)butyl' acrylate and acrylonitrile are similarly prepared. These also give films of very good solve tnresistance and low temperature flexibility properties. As little as 5 percent of acrylonitrile may be used with these estersto give copolymers of improved solvent resistance. copolymers of substantially equal proportionsof the cyano ether-ester and acrylonitrile are characterized not only by very good resistance to solvents, but also by very good heat-resistance roperties.

What is claimed is:

1. A copolymer of a cyanoether-ester having the formula CH CHCOOCHflCH) CH OCH CH CN in which n is an integer of from 1 to 2 and acrylonitrile, said copolymer containing between 30 percent and 95 percent of the ether-ester, with the balance being acrylonitrile.

2. Emulsion latices comprising copolymers ether-esters having the formula in which n is an integer of from 1 to 2, and acrylonitrile, said copolymers containing between 30 percent and 95 percent of the ether-ester, with the balance being acrylonitrile.

3. A copolymer of 3-(2-cyanoethoxy)propyl acrylate and acrylonitrile, said copolymer containing between 40 percent and percent of said acrylate, with the balance being acrylonitrile.

4. The process of forming a copolymer which comprises heating, in the presence'of a polymerization catalyst, a mixture comprising a cyanoether-ester having the formula in which n is an integer of from 1 to 2, and acrylonitrile, said mixture consisting of from 30 percent to percent of the ester, with the balance being acrylonitrile.

5. The process of forming a copolymer which comprises heating, in the presence of a polymerization catalyst, a mixture comprising 3-(2-cyanoethoxy)propyl acrylate and acrylonitrile, said mixture consisting of from 40 percent to 90 percent of the acrylate, with the balance being acrylonitrile. a

of cyano- References Cited in the file of this patent UNITED STATES PATENTS DAlelio Jan. 22, 1952 2,669,558 Mowry et a1. Feb. 16, 1954 

1. A COPOLYMER OF A CYANOETHER-ESTER HAVING THE FORMULA 